Method and device for recording data in an optical memory card

ABSTRACT

A method and a device for recording data in an optical memory card which facilitate judgment between an unrecorded region and a recorded region in the optical memory card and which prevent double writing. Record pits are formed so that data to be recorded on the optical memory card is recorded in the same way as when recorded in the MFM-RZ modulation system. Data that was recorded in the NRZI-RZ modulation system is reproduced and the modified to record in the MFM-RZ modulation system. This method forms the record pits at least every two recording intervals or less in the recorded region in the optical memory card, making it possible to judge the unrecorded region of the optical memory card from the recorded region according to presence or absence of the record pits and thereby preventing double writing.

TECHNICAL FIELD

The invention relates to a method and a device for recording data in anoptical memory card, and more particularly to a method and a device forrecording data in an optical memory card, that records data so as toform at least one record pit between two data records in a recordingregion of the optical memory card in order to improve a function ofjudging between an unrecorded region and a recorded region of theoptical memory card, thereby preventing double writing.

BACKGROUND ART

Generally, the optical memory card is a plastic card and can record andreproduce data in its recording region with a laser beam.

FIG. 7 shows a recording region 102 of an optical memory card 101. Asshown in its enlarged diagram, data recording tracks 103 for recordinginformation and guide tracks 104 formed at given intervals required fortracking control for stabilizing a radiating position of the laser beamsfor recording and reproducing are alternately disposed on the recordingregion 102.

The data recording tracks 103 and the guide tracks 104 have a differentreflection ratio. Comparing the reflection ratio of these two, the datarecording tracks 103 have a higher reflection ratio and the guide tracks104 have a lower reflection ratio.

And, a record pit 105 is a portion having a low reflection ratio, whichis formed in the data recording tracks 103, with the laser beam torecord information. The presence or not of the record pit 105 indicatesinformation to be recorded.

FIG. 8 shows a logical data structure of the recording region 102. Onthe recording region 102, read-in 111 provided for an unillustratedoptical memory card reader/writer to realize a bit synchronization atthe time of recording or reproducing and an SYNC mark 112 for theunillustrated optical memory card reader/writer to realize a framesynchronization at the time of recording or reproducing have beenrecorded, in addition to a data recording region 110 where informationis recorded.

The read-in 111 has the SYNC mark 112 recorded and record pits 105formed at given intervals.

An optical memory card reader/writer (not shown) is provided with asynchronization signal generator (not shown), scans the optical memorycard 101 at a scan rate so that a synchronization signal output from thesynchronization signal generator agrees with a signal which rises forevery one bit detected by scanning the read-in 111, and keeps the samescan rate to make bit synchronization.

And, the SYNC mark 112 is formed of record pits 105, which are arrangedin a pattern not produced by modulation, and used when the unillustratedoptical memory card reader/writer gets frame synchronization.

The frame is a bit separation to process a signal by a signal processingcircuit in the unillustrated optical memory card reader/writer. Theunillustrated optical memory card reader/writer is provided with acounter (not shown) for obtaining frame synchronization. The countercounts the synchronization signal, outputs a frame synchronizationsignal after counting up to the number of bits configuring one frame,and resets its counted number.

Since the SYNC mark 112 is recorded at the start end (or terminationend) of the frame, the unillustrated optical memory card reader/writerscans the optical memory card 101. And when the SYNC mark 112 isdetected, the number indicated by the unillustrated counter forobtaining frame synchronization is reset, thereby assuring theacquisition of frame synchronization.

And, the data recording region 110 has the SYNC mark and n sectors 113arranged as indicated by a data recording region 110-1 on each frame.The sector 113 is composed of a single or a plurality of bits.

FIG. 9 is a diagram showing an NRZI-RZ (nonreturn-to-zero change on1-return to zero) modulation system for converting data, which isrecorded in a conventionally used optical memory card, into the presenceor not of a record pit.

The NRZI-RZ modulation system is a modulation system to produce a pulseat a polarity reversion position of an NRZI (nonreturn-to-zero changeon 1) modulation system.

When data shown in FIG. 9(a) is modulated, the NRZI modulation systemreverses the polarity of a signal at the bit midpoint of data “1” asshown in FIG. 9(b).

Accordingly, the NRZI-RZ modulation system generates a pulse at apolarity reversion position of FIG. 9(b) as shown in FIG. 9(c).

Data modulated by the NRZI-RZ modulation system is recorded by forming arecord pit in the recording region of the optical memory card so as tocorrespond to the position of the pulse as shown in FIG. 9(d).

As apparent from FIG. 9(a) and FIG. 9(d), the NRZI-RZ modulation systemdoes not form a record pit on a part where data “0” is continuous.

However, before recording data on the optical memory card, the opticalmemory card reader/writer reproduces the optical memory card to detectthe presence or not of a record pit. Thus, it judges between anunrecorded region and a recorded region of the optical memory card toprevent double writing on it. Therefore, if data to be recorded in theoptical memory card has a portion where data “0” is continuous, a recordpit is not formed on the optical memory card while data “0” iscontinuing. And, it becomes hard to judge between the unrecorded regionand the recorded region, resulting in degrading a function of preventingdouble writing from being made by the optical memory card reader/writer.

SUMMARY OF THE INVENTION

Under the circumstances described above, it is an object of theinvention to provide a method and a device for recording data in anoptical memory card, which records data by a modulation system whichforms a record pit even when data to be recorded has data “0” whichcontinues, and changes the modulation system of a card recorded by theNRZI-RZ modulation system, to facilitate judgment between an unrecordedregion and a recorded region of the optical memory card, thereby keepinga function of preventing double writing from being made by an opticalmemory card reader/writer.

In order to achieve the above object, the invention relates to a methodof recording data in an optical memory card, in which data is recordedin such a manner as to form at least one record pit between two datarecords in a recording region of the optical memory card.

The recording region of the optical memory card comprises one-bitsectors in one frame, the data is modulated by an NRZI-RZ modulationsystem to record it in a sector for recording data and to reproduce asector adjacent to the sector for recording data, and if the adjacentsector has been recorded and the record pit has not been formed in boththe sector for recording data and the adjacent sector, a record pit isformed on a boundary between the sector for recording data and theadjacent sector.

The recording region of the optical memory card comprises plural-bitsectors in one frame, the data is modulated by an MFM-RZ modulationsystem to record it in a sector for recording data and to reproduce asector adjacent to the sector for recording data, and if the adjacentsector has been recorded and the record pit has not been formed in boththe sector for recording data and a record position in contact with aboundary of the adjacent sector, a record pit is formed on a boundarybetween the data-recorded sector and the adjacent sector.

The data is reproduced when the recording region of the optical memorycard has data recorded by the NRZI-RZ modulation system, and the recordpit is formed on a boundary of the record positions so as to modify torecord by the MFM-RZ modulation system when the recording region of theoptical memory card has continuous record positions where the record pithas not been recorded.

The invention also relates to a device for recording data in an opticalmemory card, which comprises means for recording data in such a manneras to form at least one record pit between two data records in arecording region of the optical memory card.

The recording region of the optical memory card comprises one-bitsectors in one frame, and wherein the recording device comprises meansfor modulating the data by an NRZI-RZ modulation system to record it ina sector for recording data, means for reproducing a sector adjacent tothe sector for recording data, and means for forming the record pit on aboundary between the sector for recording data and the adjacent sectorif the adjacent sector has been recorded and the record pit has not beenformed in both the sector for recording data and the adjacent sector.

And, the recording region of the optical memory card comprisesplural-bit sectors in one frame, and wherein the recording devicecomprises means for modulating the data by an MFM-RZ modulation systemto record it in a sector for recording data, means for reproducing asector adjacent to the sector for recording data, and means for formingthe record pit on a boundary between the sector for recording data andthe adjacent sector if the adjacent sector has been recorded and therecord pit has not been formed in both the sector for recording data anda record position in contact with a boundary of the adjacent sector.

Besides, the data recording device further comprises means forreproducing the data when the recording region of the optical memorycard has data recorded by the NRZI-RZ modulation system, and means forforming a record pit on a boundary of the record positions so as tomodify to record by the MFM-RZ modulation system when the recordingregion of the optical memory card has continuous record positions inwhich the record pit has not been recorded.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a) to 1(c) are diagrams showing an embodiment to record data onsectors of one bit in one frame;

FIG. 2 is a diagram showing the data structure of the data recorded inthe embodiment shown in FIG. 1 on a memory in a card reader/writer;

FIGS. 3(a) to 3(e) are diagrams showing an example of data modulation byan MFM-RZ modulation system;

FIGS. 4(a) to 4(c) are diagrams showing an embodiment to record data onsectors of a plurality of bits in one frame;

FIG. 5 is a diagram showing the data structure of the data recorded inthe embodiment shown in FIG. 4 on the memory in the card reader/writer;

FIGS. 6(a) to 6(c) are diagrams showing one example of modifying a cardrecorded by an NRZI-RZ modulation system into recordation by the MFM-RZmodulation system;

FIG. 7 is a diagram showing a recording region of an optical memorycard;

FIG. 8 is a diagram showing a logical data structure in a recordingregion; and

FIGS. 9(a) to 9(d) are diagrams showing an example of data modulation bythe NRZI-RZ modulation system.

BEST MODE FOR CARRYING OUT THE INVENTION

A method and device for recording data in an optical memory cardaccording to the invention will be described with reference to theaccompanying drawings.

FIG. 1 shows an embodiment in that data is recorded in one-bit sectorsin one frame. FIG. 2 shows a data structure on a memory in a cardreader/writer (not shown) of data to be recorded in the embodiment shownin FIG. 1.

Description will be made of an MFM-RZ (modified frequencymodulation-return to zero) modulation system with reference to FIG. 3.

The MFM-RZ modulation system is a modulation system to generate a pulsein a polarity reversion position of an MFM (modified frequencymodulation) system.

When data shown in FIG. 3(a) is modulated, the MFM system reverses apolarity at a bit midpoint of data “1” and a bit division position wheredata “0” is continuous as shown in FIG. 3(b).

Accordingly, the MFM-RZ modulation system produces a pulse at thepolarity reversion position of FIG. 3(b) as shown in FIG. 3(c).

And, a conventionally used NRZI-RZ (nonreturn-to-zero change on 1-returnto zero) modulation system is a modulation system (see FIG. 3(e)) whichgenerates a pulse at a polarity reversion position of an NRZI(nonreturn-to-zero change on 1) modulation system (see FIG. 3(d)).

When data “0” is continuous, the NRZI-RZ modulation system does notgenerate a pulse, while the MFM-RZ modulation system generates a pulsebetween at least two recording intervals.

Therefore, when data with continuous repeated “0” is reproduced, theNRZI-RZ modulation system cannot distinguish the region having thecontinuous data “0” from an unrecorded region, while the MFM-RZmodulation system can distinguish.

To record data in one-bit sectors in one frame as shown in FIG. 1(a),data is stored on the memory in a reader/writer (not shown) as shown inFIG. 2, in which data of sector 0 is arranged in direction X, and dataof sector 0 to data of sector 39 are arranged in order of increasingnumber in direction Y.

When data of sector 0, e.g., data of S00000=“1” and S00001=“0”, arerecorded in an unrecorded card, data are recorded by the NRZI-RZmodulation system as shown in FIG. 1(b). The NRZI-RZ modulation systemis used because the sector is composed of one bit in one frame, data isnot recorded continuously and data “0” is not continuous.

To record data of sector 1, namely data of S01000=“1” and S01001=“0”,into the card having its sector 0 already recorded, data is alsorecorded by the NRZI-RZ modulation system, and before or after recordingthe data, the data recorded in sector 0 is reproduced, and a record pitis formed on a boundary between sector 0 and sector 1 as shown in FIG.1(c) as required (when both data in sector 0 and sector 1 are When datais recorded as described above, in the same way as the MFM-RZ modulationsystem is used to record data, the presence or not of a record pit canbe detected to judge between the unrecorded region and the recordedregion of the optical memory card, and double writing in the opticalmemory card can be prevented.

FIG. 4 shows an embodiment that data is recorded in multiple-bit sectorsin one frame. FIG. 5 shows the structure of data, which is recorded inthe embodiment shown in FIG. 4, on the memory within a cardreader/writer (not shown).

To record data in four-bit sectors in one frame shown in FIG. 4(a), datais stored in the memory within the reader/writer (not shown) as shown inFIG. 5. In the card, data S00000, S00272, S00544 and S00816 with X=0shown in FIG. 5 are recorded in sector 0 of the first frame shown inFIG. 4(a), and data S00001, S00273, S00545 and S00817 with X=1 as shownin FIG. 5 are recorded in sector 0 of the second frame as shown in FIG.4(a).

To record data in four-bit sectors in one frame, the MFM-RZ modulationsystem is employed. In view of the structure of the sector, because dataof at least four bits are continuously recorded within one frame.Recording of data of sector 0, e.g., data such as S00000=“0”,S00001=“1”, S00272=“0”, S00273=“0”, S00544=“1”, S00545=“0”, S00816=“0”and S00817=“0” in an unrecorded card is as shown in FIG. 4(b).

Then, when data of sector 1 is recorded on the card having sector 0recorded, for example data of S10000=“0”, S10001=“1”, S10272=“0”,S10273=“0”, S10544=“1”, S10545=“0”, S10816=“0” and S10817=“0” arerecorded as shown in FIG. 4(c).

In this case, data of sector 0 is also reproduced before or afterrecording data into sector 1 to form a record pit on a boundary betweensector 0 and sector 1 as required so to have the same boundary betweensector 0 and sector 1 as recorded by the MFM-RZ modulation system.

FIG. 6 shows an example that a card recorded by the NRZI-RZ modulationsystem is modified so to be recorded by the MFM-RZ modulation system.

When the card recorded by the NRZI-RZ modulation system is modified soto be recorded by the MFM-RZ modulation system, the original cardrecorded by the NRZI-RZ modulation system can be modified to adopt theMFM-RZ modulation system (same as the MFM-RZ modulation system) by thesame method even if data are discontinuous as in the one-bit sectors inone frame or data are continuous as in the sectors of a plurality ofbits in one frame.

Data “00000110100” as shown in FIG. 6(a) becomes a signal to generate apulse at a bit midpoint of data “1” as shown in FIG. 6(b) by the NRZI-RZmodulation system, and a record pit is formed on the card so tocorrespond to the position where the pulse is generated.

Data shown in FIG. 6(a) also becomes a signal to generate a pulse at abit midpoint of data “1” and at the position of a bit breakpoint whendata “0” is continuous by the MFM-RZ modulation system as shown in FIG.6(c).

It is apparent from FIG. 6(b) and FIG. 6(c) that to change the recordmade by the NRZI-RZ modulation system into one made by the MFM-RZmodulation system, it is done satisfactorily by additional formation ofa record pit at the position of a bit breakpoint when data “0” iscontinuous.

Therefore, the unillustrated card reader/writer reproduces the cardwhich was recorded by the NRZI-RZ modulation system and forms a recordpit on the card by the MFM-RZ modulation system to record data, so thatthe NRZI-RZ modulation system can be changed to the MFM-RZ modulationsystem.

And, the unillustrated card reader/writer detects the presence or not ofa record pit in view of the reproduced signal to judge between theunrecorded region and the recorded region of the optical memory card andextracts a synchronization component from the reproduced signal as adata signal. But, the record pit formed when the NRZI-RZ modulationsystem is changed to the MFM-RZ modulation system is not included in thesynchronization component and does not affect on the data signal.Therefore, the card modified to the MFM-RZ modulation system can also bereproduced by a card reader/writer of the NRZI-RZ modulation system.

INDUSTRIAL APPLICABILITY

The invention can be applied to a data recording method and device foran optical memory card. The invention is configured to record data toform at least one record pit between two data records in a recordingregion of the optical memory card and has an improved function forjudging between a unrecorded region and a recorded region of the opticalmemory card to facilitate prevention of double writing.

What is claimed is:
 1. A method of recording data in an optical memorycard, in which data is discontinuously recorded, by forming no more thanone pit in each sector of the optical memory card, the method comprisingthe steps of: storing data to be written in a memory; using NRZI-RZmodulation to write data from the memory into contiguous sectors thatcomprise a frame by recording one bit per sector; and successivelyforming a pit in contact with a boundary between a first sector and animmediately adjacent sector as long the memory shows that both the firstsector and the immediately adjacent sector contain data and the data forboth sectors results in no pit being formed according to NRZI-RZmodulation, the pit being formed at the boundary within the immediatelyadjacent sector, thereby ensuring that no overwriting of data occurs. 2.A method of recording data in an optical memory card, in which data isdiscontinuously recorded, by forming a plurality of pits in each sectorof the optical memory card, the method comprising: storing data to bewritten in a memory; using MFM-RZ modulation to write data from thememory into contiguous sectors in the frame by recording more than onebit per sector; and successively forming a pit in contact with aboundary between a first sector and an immediately adjacent sector aslong the memory shows that both the first sector and the immediatelyadjacent sector contain data and the data for the most significant bitof the first sector and the least significant bit of the immediatelyadjacent sector both result in no pit being formed according to MFM-RZmodulation, the pit being formed at the boundary within the immediatelyadjacent sector, thereby ensuring that no overwriting of data occurs. 3.A device for recording data in an optical memory card, in which data isdiscontinuously recorded, by forming no more than one pit in each sectorof the optical memory card, the device comprising: means for storingdata to be written means for modulating the data by an NRZI-RZmodulation system to record the data in each sector in a frame, one bitper sector; means for successively forming a pit in contact with aboundary between a first sector and an immediately adjacent sector aslong the stored data shows that both the first sector and theimmediately adjacent sector contain data and the data for both sectorsresults in no pit being formed according to NRZI-RZ modulation, the pitbeing formed at the boundary within the immediately adjacent sector,thereby ensuring that no overwriting of data occurs.
 4. A device forrecording data in an optical memory card, in which data isdiscontinuously recorded, by forming a plurality of pits in each sectorof the optical memory card, the method comprising: means for storingdata to be written; means for using MFM-RZ modulation to write data fromthe memory into contiguous sectors in the frame by recording more thanone bit per sector; and means for successively forming a pit in contactwith a boundary between a first sector and an immediately adjacentsector as long the memory shows that both the first sector and theimmediately adjacent sector contain data and the data for the mostsignificant bit of the first sector and the least significant bit of theimmediately adjacent sector both result in no pit being formed accordingto MFM-RZ modulation, the pit being formed at the boundary within theimmediately adjacent sector, thereby ensuring that no overwriting ofdata occurs.